portfolio-optimiser/tests/test_costsim.py

"""S3.6 costsim — unit tests: pricing load/fail-fast, deterministic estimate, table, CLI.

Load-bearing detach seams live in ``test_costsim_loadbearing.py``; these are the happy-path +
schema unit tests.
"""

from __future__ import annotations

import json
from pathlib import Path

import pytest
from pydantic import ValidationError

from portfolio_optimiser import costsim

_VALID_PRICING = {
    "source": "unit-test prices",
    "date": "2026-07-15",
    "models": {
        "m-cheap": {
            "ore_per_1k_tokens": 10,
            "quality_guidance": {"note": "cheap draft model", "source": "test-src 2026-07-15"},
        },
        "m-dear": {
            "ore_per_1k_tokens": 50,
            "quality_guidance": {"note": "stronger reasoning", "source": "test-src 2026-07-15"},
        },
    },
}


def _write(tmp_path: Path, data: dict) -> Path:
    p = tmp_path / "pricing.json"
    p.write_text(json.dumps(data), encoding="utf-8")
    return p


def test_load_pricing_valid(tmp_path: Path) -> None:
    pricing = costsim.load_pricing(_write(tmp_path, _VALID_PRICING))
    assert pricing.models["m-cheap"].ore_per_1k_tokens == 10
    assert pricing.source == "unit-test prices"


def test_load_pricing_bundled_default() -> None:
    """No path → the packaged data/pricing.example.json loads and prices the local model."""
    pricing = costsim.load_pricing()
    assert "qwen3:4b" in pricing.models


def test_load_pricing_missing_file_raises(tmp_path: Path) -> None:
    with pytest.raises(FileNotFoundError):
        costsim.load_pricing(tmp_path / "nope.json")


def test_load_pricing_missing_provenance_raises(tmp_path: Path) -> None:
    bad = {"models": _VALID_PRICING["models"]}  # no source/date
    with pytest.raises(ValidationError):
        costsim.load_pricing(_write(tmp_path, bad))